1. Field of the Invention
The present invention relates to a power transmission apparatus for an electric bending endoscope whose bending portion is to be electrically operated to be bent.
2. Description of the Related Art
In an electric bending endoscope, a bending portion to be operated to be bent is provided at the distal end portion of an elongate insertion portion to be inserted into a body cavity, and an operation portion to be held and operated by an operator is coupled to the proximal end portion of the insertion portion. The operation portion is provided with a bending switch and includes a motor and an angle mechanism therein, and an angle wire extending out of the angle mechanism is inserted through the insertion portion, and coupled to the distal end portion of the bending portion. When the bending switch is operated, the motor actuate the angle mechanism to move the angle wire back and forth, and so the bending portion is operated to be bent. Here, a clutch mechanism is provided between the motor and the angle mechanism. When the clutch mechanism is operated, the motor is separated from the angle mechanism, and the angle mechanism is free, and so the bending portion becomes linear easily. As such a clutch mechanism, Jpn. Pat. Appln. KOKAI Publication No. 5-95896 has disclosed a clutch mechanism to be actuated by manually operating an operation lever, and Jpn. Pat. Appln. KOKAI Publication No. 2003-275168 has disclosed a clutch mechanism to be actuated by an electric drive mechanism.